Distilling Hydrometer: The Proof is in the Measurements!
What’s a distilling Hydrometer?
A hydrometer has been calibrated to only measure the specific gravity (SG) of the liquid water mixture. In brewing a sugar wash solution density (SG) is measured to record the opening original Gravity (OG).
At the end of fermentation, you again measure the final SG of the mixture FG. You then subtract the OG from the FG x factor to get to the potential alcohol you can expect from your batch. This also helps you with making cuts.
How to use an alcohol hydrometer for distilling
Temperature Compensation
An alcohol spirit distilling hydrometer is calibrated at 20°C (68°C) to measure the pure spirit’s % ABV accurately. However, if the actual temperature of the spirit being measured is higher (making the spirit less dense) or lower (more dense) than the set 20°C (68°C) on the meter, it will result in an inaccurate reading.
To obtain a correct measurement, you should cool the spirit sample to match the hydrometer’s calibrated temperature. Alternatively, a more accurate DIY method is to estimate
Estimate The Alcohol Temperature Reading Simply
For the DIY the following calculation is fine.
The rule of thumb is for every 1°C over 20°C minus 0.33% off the actual spirit meter reading.
| Example ABV | = 94% |
| Spirit temp at parrot | = 30°C |
| Factor | = .33% |
| Difference in temp | = 20 – 30 = 10 X .33 = 3.33 |
| ABV calc | = 94 – 3.33 |
| ABV | = 90.67 % |
Can A Distilling Hydrometer Be Used To Measure Alcohol ABV?
Yes, it can.
In the initial phases of fermentation, a hydrometer is used to determine the measured alcohol content (ABV) you can expect from fermentation by density tests (SG).
OG – FG X Factor = Potential alcohol in the sugar wash.
To measure the ABV proof in your distilled spirit you will need an alcoholmeter and not a distilling hydrometer.
Should you need a distilling hydrometer?
The purpose of a hydrometer is to measure density accurately whether it is to measure the brew or ABV of distillate. As a brewer, you can’t do without this tool.
Last Updated on Jan 24, 2024 by The Brew Mechanic
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With 35 years of knowledge of being a chemical engineer in alcohol manufacturing plants, my mission is to teach the next generation of home distilling alcohol brewers at a supernatural speed.
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